发表机构
Stanford University; Nanyang Technological University（斯坦福大学; 南洋理工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用交通激发的桥梁作为持续地震源，通过DAS记录实现河流走廊时移成像，监测洪水期间地下速度变化，支持水文与基础设施监测。
AI 中文摘要
河流走廊调节着动态的河流-地下水交换，并支撑着重要的交通基础设施，然而连续的地下监测仍受限于稀疏的点传感器和低频次的时移勘测。在极端洪水事件期间，当瞬态饱和、孔隙压力积聚和结构冲刷驱动复杂的流体-力学变化，威胁河岸斜坡稳定性和桥梁基础时，弥补这一观测空白至关重要。在此，我们证明交通激发的公路桥梁可作为持续、空间固定的地震源；其振动通过路侧电信光纤上的分布式声学传感（DAS）记录，能够实现河流走廊的时移成像。我们利用韩国京釜高速公路沿线的暗光纤记录，在2025年7月创纪录的季风洪水期间评估了该方法，目标是跨越美湖河的一座430米多跨桥梁。车辆冲击激发桥面的弯曲共振，在周围地面产生基阶瑞利波的离散频谱梳；这些3-6 Hz的波传播超过400米，横跨两岸，对直至基岩的冲积层段进行成像。由于桥梁结构几何约束了震源位置和主导模态频率，虚拟震源道集在5分钟的弹道波叠加内实现快速收敛，并在记录期间具有高波形重复性。相对地震速度（dv/v）监测解析出洪水通过期间与强降水和河流水位上升相关的速度下降，最大达1.0%，与河岸沉积物的水文软化一致。这些结果表明，交通激发的桥梁提供持续、可重复的地震照明，将路侧电信电缆转变为用于水文地球物理和民用基础设施应用的密集阵列。
英文摘要
Fluvial corridors mediate dynamic river-groundwater exchanges and support major transportation infrastructure, yet continuous subsurface monitoring remains limited by sparse point sensors and infrequent time-lapse surveys. Addressing this observational gap is critical during extreme flood events, when transient saturation, pore-pressure buildup, and structural scour drive complex hydro-mechanical changes that threaten both riparian slope stability and bridge foundations. Here, we demonstrate that traffic-excited highway bridges act as persistent, spatially fixed seismic sources; their vibrations, recorded on roadside telecommunication fiber with Distributed Acoustic Sensing (DAS), enable time-lapse imaging of river corridors. We evaluate this approach using dark fiber recordings along South Korea's Gyeongbu Expressway during a record monsoon flood in July 2025, targeting a 430 m multi-span bridge crossing the Miho River. Vehicle impacts excite flexural resonances of the bridge deck, generating a discrete spectral comb of fundamental-mode Rayleigh waves in the surrounding ground; these 3-6 Hz waves propagate beyond 400 m across both riverbanks to image the alluvial section down to bedrock. Because bridge-structure geometry constrains the source location and dominant modal frequencies, virtual source gathers achieve rapid convergence within 5 min of ballistic wave stacking with high waveform repeatability over the recording period. Relative seismic velocity (dv/v) monitoring resolves velocity drops up to 1.0% during flood passage associated with heavy precipitation and river stage rise, consistent with hydrological softening of the riparian sediments. These results demonstrate that traffic-excited bridges provide persistent, repeatable seismic illumination, turning roadside telecommunication cables into dense arrays for both hydrogeophysical and civil infrastructure applications.
